In supermarket, retail store, department store and other shops, a security store system (e.g. refer to Patent Document 1) of a gate structure is sometimes adopted to prevent thefts and pickpockets.
This security store system is structured as follows: a gate in which a wireless device for realizing a near-distance wireless communication is built is arranged at the entrance/exit of a store, and a security tag is adhered on the commodity displayed in the store as a wireless tag provided with a resonant circuit. When people carrying a commodity adhered with the security tag, that is, a commodity with an effective security tag, passes the gate, the wireless device built in the gate carries out a near-distance wireless communication to make the resonant circuit of the security label resonate to detect a tag signal, then an alarm device configured at a given position sounds an alarm.
In the case where the security store system above is applied, when a commodity is off a checkout counter, a tag signal eliminating signal should be sent to the resonant circuit of the security tag to destroy the resonant circuit so that even if the wireless device built in the gate carries out a near-distance wireless communication, the resonant circuit of the security tag will not resonate to send a tag signal (hereinafter referred to as ‘eliminate the security tag’).